Calibration method and device of PET system, storage medium and computer equipment

Abstract

The application discloses a PET system correction method and device, a storage medium and computer equipment, relates to the medical image technical field, and mainly can reduce the efficiency correction cost of the PET system detector, and simultaneously reduces the efficiency correction difficulty of the PET system detector. The method comprises the following steps: acquiring single photon counting values collected by each detector in a PET system, wherein the single photon counting value is the number of single photons generated by a radioactive source phantom and collected by each detector in the process that the radioactive source phantom moves along the axial direction of the PET system, and the length of the radioactive source phantom is less than the axial field of view length of the PET system; calculating efficiency correction coefficients of each detector based on the single photon counting values collected by each detector; and determining efficiency correction coefficients of corresponding original coincidence event data of the PET system according to the efficiency correction coefficients of each detector, wherein the efficiency correction coefficients of the original coincidence event data are used for correcting the detection efficiency of the PET system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of medical image technology, in particular to a PET system correction method and device, a storage medium and a computer equipment. BACKGROUND

[0002] PET (Positron Emission Computed Tomography) system is one of the most advanced large medical diagnostic imaging equipment today. In addition to showing morphological structure, PET system can provide functional information about organs and their lesions at the molecular level using in vivo metabolism, and has excellent performance in diagnosing diseases such as tumors, cardiovascular and nervous system. The working principle of PET system is to inject a drug containing a radionuclide into the subject to be examined, the radionuclide decays to produce a positron, the positron annihilates with the surrounding negative electron to produce a pair of back-to-back gamma photons, the gamma photons pass through the subject to be examined and are received and recorded by the PET system detector, wherein the detector receives and records the gamma photons, which is called a single event. According to the receiving time and time window setting, the gamma photons form a coincidence event, and the PET system reconstructs the image according to the coincidence event to obtain the distribution map of the positron emitting nuclide. In the process of PET system data acquisition, since the PET system is composed of many detectors, there are differences in the efficiency of each detector. If the efficiency difference of the detector is not corrected, it will cause the difference between the data collected by the PET system and the data assumed by the reconstruction model, resulting in artifacts and inaccurate quantification in the PET system reconstruction image. In order to solve this problem, we need to correct the efficiency of the data collected by the PET system.

[0003] At present, a phantom with a length that can cover the axial field of view of the PET system is usually used to collect coincidence events, and then the efficiency correction coefficient of the PET system detector is calculated by means of the collected coincidence events. However, when the axial field of view of the PET system is very large, if the efficiency correction coefficient is still calculated in this way, a very long phantom is needed, which will cause problems such as difficulty in manufacturing, high cost, and large weight of the phantom, which will also increase the difficulty of operation and further affect the efficiency correction progress of the PET system detector. SUMMARY

[0004] The present application provides a PET system correction method and device, a storage medium and a computer equipment, which can reduce the efficiency correction cost of the PET system detector, reduce the efficiency correction difficulty of the PET system detector, and improve the efficiency correction progress of the PET system detector.

[0005] According to a first aspect of the present application, a PET system correction method is provided, comprising:

[0006] acquiring single photon count values collected by each detector in a PET system, wherein the single photon count values are the number of single photons generated by a radioactive source phantom collected by each detector in the process that the radioactive source phantom moves along an axial direction of the PET system, and the length of the radioactive source phantom is less than the axial field of view length of the PET system;

[0007] calculating efficiency correction coefficients of the detectors based on the single photon count values collected by each detector;

[0008] determining efficiency correction coefficients of the PET system corresponding to raw coincidence event data according to the efficiency correction coefficients of the detectors, wherein the efficiency correction coefficients of the raw coincidence event data are used to correct the detection efficiency of the PET system.

[0009] Optionally, the acquiring single photon count values collected by each detector in a PET system comprises:

[0010] determining an effective radioactive site of the radioactive source phantom according to the geometric parameter information of the radioactive source phantom;

[0011] based on the head real-time position information, the tail real-time position information along the axial direction of the PET system and the position information of the detectors in the effective radioactive site, sequentially accumulating the number of single photons collected by each detector to obtain the single photon count values of each detector.

[0012] Optionally, the method further comprises:

[0013] controlling the radioactive source phantom to move through each detector along the axial center line of the PET system in a uniform linear motion, wherein the radioactive source phantom is a uniform axial center symmetric phantom, and the axial center line of the radioactive source phantom coincides with the axial center line of the PET system.

[0014] Optionally, the method further comprises:

[0015] determining the half-life of the radioactive source phantom;

[0016] based on the half-life, determining the moving speed and the moving times of the radioactive source phantom along the axial center line of the PET system.

[0017] Optionally, the calculating efficiency correction coefficients of the detectors based on the single photon count values collected by each detector comprises:

[0018] accumulating the single photon count values collected by each detector to obtain the single photon count sum collected by the PET system;

[0019] determine a single photon counting mean value based on the number of the detectors and the single photon counting values, and determine a ratio of the single photon counting mean value to each single photon counting value as an efficiency correction coefficient of each detector.

[0020] Optionally, the determining the efficiency correction coefficient of the PET system corresponding to the raw coincidence event data according to the efficiency correction coefficients of the detectors comprises:

[0021] determining a first detector and a second detector corresponding to the raw coincidence event data;

[0022] multiplying the efficiency correction coefficient of the first detector and the efficiency correction coefficient of the second detector to obtain the efficiency correction coefficient of the raw coincidence event data.

[0023] Optionally, after the efficiency correction coefficient of the raw coincidence event data is obtained by multiplying the efficiency correction coefficient of the first detector and the efficiency correction coefficient of the second detector, the method further comprises:

[0024] multiplying the efficiency correction coefficient of the raw coincidence event data and the raw coincidence event data to obtain corrected coincidence event data.

[0025] According to a second aspect of the present application, a correction device of a PET system is provided, comprising:

[0026] an acquisition unit configured to acquire single photon counting values collected by each detector in the PET system, wherein the single photon counting values are the number of single photons generated by a radioactive source phantom in a process that the radioactive source phantom moves along an axial direction of the PET system through each detector, and the length of the radioactive source phantom is less than the axial field of view length of the PET system;

[0027] a calculation unit configured to calculate efficiency correction coefficients of the detectors based on the single photon counting values collected by each detector;

[0028] a determination unit configured to determine efficiency correction coefficients of raw coincidence event data of the PET system according to the efficiency correction coefficients of the detectors, wherein the efficiency correction coefficients of the raw coincidence event data are used to correct the detection efficiency of the PET system.

[0029] According to a third aspect of the present application, a computer readable storage medium is provided, which stores a computer program, and the program is executed by a processor to implement the above-mentioned correction method of the PET system.

[0030] According to a fourth aspect of the present application, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the correction method of the PET system.

[0031] According to the correction method, device, storage medium and computer device of the PET system provided by the present application, compared with the current method of collecting coincidence data by using a phantom with a length capable of covering the axial field of view of the PET system, and then calculating the PET system efficiency correction coefficient by means of the collected coincidence data, the present application acquires single photon counting values collected by each detector in the PET system, wherein the single photon counting value is the number of single photons generated by the radioactive source phantom and collected by each detector in the process of moving the radioactive source phantom along the axial direction of the PET system, and the length of the radioactive source phantom is less than the length of the axial field of view of the PET system; and the efficiency correction coefficient of each detector is calculated based on the single photon counting values collected by each detector; and finally, the efficiency correction coefficient of the original coincidence event data corresponding to the PET system is determined according to the efficiency correction coefficients of each detector, wherein the efficiency correction coefficient of the original coincidence event data is used to correct the detection efficiency of the PET system. Thus, by using a shorter uniform radioactive source phantom, the radioactive source axial center line is required to be aligned with the PET system axial center line, at the same time, the radioactive source phantom is controlled to move along the PET system axial center line to collect single photon counting values of each detector, then the efficiency correction coefficients of each detector are calculated according to each single photon counting value, and finally, the original coincidence event data collected by the PET system is corrected, so that the detector efficiency correction coefficient can be quickly and accurately determined, and the efficiency correction cost of the PET system detector can be reduced, thereby avoiding the problems of difficulty in manufacturing the long phantom, high manufacturing cost, great difficulty in operating the phantom and long operation time caused by using the long phantom to determine the detector efficiency correction coefficient in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are included to provide a further understanding of the present application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and together with the description serve to explain the present application. In the drawings:

[0033] Figure 1 A flow chart of a correction method of a PET system is shown according to an embodiment of the present application;

[0034] Figure 2 A flow chart of another correction method of a PET system is shown according to an embodiment of the present application;

[0035] Figure 3 A schematic diagram of a radioactive source phantom moving along the axial field of view of a PET system is shown according to an embodiment of the present application;

[0036] Figure 4 A structural schematic diagram of a correction device of a PET system provided by an embodiment of the present application is shown.

[0037] Figure 5 A physical structure schematic diagram of a computer device provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0038] Hereinafter, the present application will be described in detail with reference to the accompanying drawings and in conjunction with embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0039] At present, the mode of using a phantom with a length covering the axial field of view of the PET system to collect coincidence events, and then calculating the efficiency correction coefficient of the PET system detector by means of the collected coincidence events, results in increasing the efficiency correction cost of the PET system detector and reducing the efficiency correction progress of the PET system detector.

[0040] In order to solve the above problems, an embodiment of the present application provides a PET system correction method, as shown in the following Figure 1 The method comprises the following steps.

[0041] 101. Obtain single photon counting values collected by each detector in the PET system, wherein the single photon counting value is the number of single photons generated by the radioactive source phantom in the process of the radioactive source phantom moving along the axial direction of the PET system through each detector, and the length of the radioactive source phantom is less than the length of the axial field of view of the PET system.

[0042] The radioactive source phantom is a uniform-shaped phantom with a containing space inside, and the containing space of the phantom is injected with a PET system tracer solution (which can be a drug containing a radionuclide) to use the phantom as a radioactive source capable of emitting photons. The PET system comprises a plurality of detectors, and the number of specific detectors is not limited by the embodiments of the present application. The axial field of view of the PET system is a space in which the radioactive source phantom can be placed and the photons generated by the radioactive source can be collected.

[0043] For the embodiment of the present application, a uniform radioactive source phantom with a length less than the axial field of view length of the PET system is placed on the bed plate, and the axial center line of the radioactive source and the axial center line of the PET system are aligned, and then the radioactive source phantom is controlled by the bed plate to move along the axial direction of the PET system from outside one end of the PET system to outside the other end of the PET system, thereby passing through each detector in the PET system. During the movement, when the radioactive source phantom passes through any one detector, the number of single photons collected by the any one detector is cumulatively determined, thereby the single photon count values collected by each detector can be determined, and finally the efficiency correction coefficient of each detector is determined according to the single photon count values collected by each detector, and then the detection efficiency of the PET system is corrected according to the efficiency correction coefficient of each detector. Thus, using a shorter phantom as a radioactive source can reduce the efficiency correction cost of the PET system detector and reduce the operation difficulty. In addition, since the number of single photon events in a unit time is much larger (usually ten times) than the number of coincidence events, using single photon events can reduce the time consumption of acquisition. In addition, the acquisition of coincidence events requires long-time acquisition, which is affected by factors such as inconsistent count loss, resulting in a decrease in the accuracy of the calculated efficiency correction value. It should be noted that the length of the radioactive source phantom in the embodiment of the present application can be less than the axial field of view length of the PET system, or can be not less than the axial field of view length of the PET system, which can be selected according to the needs of the tester.

[0044] 102. Calculate the efficiency correction coefficient of each detector based on the single photon count values collected by each detector.

[0045] For the embodiment of the present application, the computer device can be connected with the PET system, and the computer device can acquire the single photon count values collected by each detector when the radioactive source phantom moves along the axial direction of the PET system and passes through each detector. Then, the computer device calculates the single photon count mean value commonly corresponding to each detector according to the single photon count values corresponding to each detector, and finally determines the efficiency correction coefficient of each detector according to the single photon count mean value and the single photon count values corresponding to each detector. Thus, by determining the single photon count values collected by each detector to calculate the efficiency correction factor of each detector, the time consumed for determining the detector efficiency correction coefficient by acquiring the original coincidence event data can be avoided, thereby the present application improves the correction efficiency of the detector.

[0046] 103. Determine the efficiency correction coefficient of the original coincidence event data corresponding to the PET system according to the efficiency correction coefficient of each detector, wherein the efficiency correction coefficient of the original coincidence event data is used to correct the detection efficiency of the PET system.

[0047] For the embodiment of the present application, because the data obtained by the PET system scanning is the original coincidence event data, and each single event data collected by two detectors constitutes an original coincidence event data, after the efficiency correction coefficient corresponding to each detector is determined, the efficiency correction coefficient of the PET system corresponding to the original coincidence event data also needs to be determined, and the efficiency correction coefficient of the PET system corresponding to the original coincidence event data is determined by the two detector efficiency correction coefficients corresponding to the coincidence time. Thus, by using a shorter uniform radioactive source phantom, the radioactive source axial center line and the PET system axial center line are required to be aligned, at the same time, the radioactive source phantom is controlled to move along the PET system axial center line, the single photon count values of each detector are collected, then the detector efficiency correction coefficients are calculated according to the single photon count values, and finally the original coincidence event data collected by the PET system is corrected, so that the detector efficiency correction coefficients can be quickly and accurately determined, and the efficiency correction cost of the PET system detector can be reduced, and the problems of difficult manufacturing, high manufacturing cost, large operation difficulty and long operation time of the long phantom for determining the detector efficiency correction coefficients in the prior art are avoided.

[0048] Further, in order to better illustrate the above-mentioned correction process of the PET system, as a refinement and expansion of the above-mentioned embodiment, the embodiment of the present application provides another correction method of the PET system, as shown in Figure 2 The method comprises:

[0049] 201. Determine the effective radiation site of the radioactive source phantom according to the geometric parameter information of the radioactive source phantom.

[0050] The radioactive source phantom is a uniform axial center symmetric phantom, such as a uniform cylindrical source, a circular ring source or an axial center symmetric source such as a spherical source, the axial center line of the radioactive source phantom is aligned with the axial center line of the PET system, that is, the radioactive source phantom is symmetric about the axial center line of the PET system, and the radioactive source phantom does not need to cover the entire axial field of view of the PET system. Thus, by using a shorter phantom that does not need to cover the axial field of view of the PET system to correct the efficiency of the PET system detector, the problems of difficult manufacturing and difficult operation of the long phantom can be avoided, so that the present application can reduce the difficulty of efficiency correction of the PET system detector, and also can reduce the efficiency correction cost of the PET system detector.

[0051] Specifically, the embodiment of the present application adopts a shorter uniform radioactive source phantom, wherein the length of the radioactive source phantom is less than the length of the axial field of view of the PET system, and then the effective radiation range of the radioactive source phantom is selected to limit the range of single events detected by the detector to ensure that the radioactive source received by each detector is uniform, thereby improving the accuracy of the determination of the detector efficiency correction coefficient. For example, if the total length of the radioactive source phantom is 20 cm, 6 cm can be selected as the effective radiation range on the left and right of the axial center of the radioactive source phantom, and each detector in the PET system collects single photons within the effective radiation range.

[0052] 202、Based on the head real-time position information, the tail real-time position information of the effective radiation part along the axial direction of the PET system, and the position information of each detector, the number of single photons collected by each detector is sequentially accumulated to obtain a single photon count value of each detector.

[0053] The single photon count value is the total number of single photons collected by any one detector. The real-time position information is the position information of the head and tail of the effective radiation part of the radioactive source phantom at each time when the effective radiation part moves along the axial direction of the PET system. The head of the radioactive source phantom is the front part based on the moving direction, and the tail is the rear part based on the moving direction.

[0054] Specifically, each detector only accumulates single events when the effective radiation part of the radioactive source phantom passes through the detector. In order to determine whether the effective radiation part passes through any one detector, the head real-time position, the tail real-time position of the effective radiation part along the axial direction of the PET system, and the position information of each detector need to be determined first. The above position information can be determined by the bed plate position. For example, based on the bed plate, a rectangular coordinate system is established. First, the position information of the effective radiation part on the bed plate is determined. Then, when the bed plate position is x, it is determined that the head of the effective radiation part starts to reach the first ring detector, and when the bed plate position is y, it is determined that the tail of the effective radiation part starts to leave the first ring detector. Therefore, the number of single photons detected by the first ring detector is accumulated when the bed plate position is between x and y, thereby obtaining the single photon count value of each detector.

[0055] Specifically, in the above scenario of obtaining the single photon count value of each detector, the uniform radioactive source phantom needs to be moved along the axial direction of the field of view of the PET system scanner to pass through each detector. Based on this, the method comprises: controlling the radioactive source phantom to move at a uniform speed along the axial center line of the PET system to pass through each detector, wherein the radioactive source phantom is a uniform axial center symmetric phantom, and the axial center line of the radioactive source phantom coincides with the axial center line of the PET system.

[0056] In this embodiment of the invention, after selecting the effective radiation site of the radiation source phantom, the radiation source phantom can be placed on a movable bed board. Simultaneously, devices such as CT (Computed Tomography) can be used to correct the collinearity between the centerline of the radiation source phantom and the axial centerline of the PET system. For example... Figure 3 As shown, the phantom of the radioactive source is controlled by a bed board to move along the axial centerline of the PET system. The movement range is required to allow the effective emission portion of the phantom to move from one end of the PET system to the other end, enabling the phantom to pass through all detectors on the PET system. When the phantom passes any detector, that detector can collect a single event, i.e., a single photon emitted by the phantom. In this embodiment, the computer controls the uniform radioactive source phantom to move along the axial direction of the PET system scanner's field of view in a continuous, uniform linear motion. This allows the uniform radioactive source phantom to cover the entire axial field of view of the detector. The resulting single-photon count value is the count value covering the entire axial field of view of the detector. This allows the efficiency correction coefficient, determined based on the single-photon count value, to be used to correct the detector's detection efficiency. This solves the problem in traditional technologies where, when the phantom length is greater than the axial field of view of the PET system, it is difficult to conveniently correct the detection efficiency of the PET system.

[0057] Meanwhile, as the radioactive source phantom moves with the bed board, the number of moves and the speed of movement can be determined based on the half-life of the radioactive source phantom. Based on this, the method includes: determining the half-life of the radioactive source phantom; and determining the speed and number of moves of the radioactive source phantom along the axial centerline of the PET system based on the half-life.

[0058] Half-life is the time required for the number of radioactive single photons generated by the radioactive source motif to decay to half of its original value during the decay process.

[0059] Specifically, during the process of controlling the uniform movement of the radioactive source phantom, if the radioactive source phantom has a long half-life, it can be controlled to perform a single uniform movement within the axial field of view of the PET system, or it can undergo multiple repetitive movements or multiple reciprocating movements. If the radioactive source phantom has a short half-life, it needs to be controlled to rapidly perform multiple repetitive movements or multiple reciprocating movements within the axial field of view of the PET system. This avoids instability in the number of photons received by each detector due to the half-life of the radioactive source phantom, thereby improving the calibration accuracy of each detector.

[0060] 203. The single-photon count values ​​collected by each detector are summed to obtain the single-photon count sum collected by the PET system.

[0061] Wherein, the single photon count sum is the sum of the single photon count values detected by each detector, and the embodiment of the application adds the single photon count values corresponding to each detector to obtain the single photon count sum corresponding to each detector, that is, the single photon count sum corresponding to the PET system.

[0062] 204. Determine the single photon count mean based on the number of detectors and the single photon count sum, and determine the ratio of the single photon count mean to each single photon count value as the efficiency correction coefficient of each detector.

[0063] Specifically, the efficiency correction coefficient of each detector can be determined by the following formula:

[0064]

[0065] Wherein, n i represents the efficiency correction coefficient of any one detector, m represents the number of detectors, s i represents the single photon count value corresponding to any one detector, and i represents the serial number of the detector, so that the efficiency correction coefficient of each detector can be calculated according to the above formula.

[0066] 205. Determine the first detector and the second detector corresponding to the original coincidence event data of the PET system.

[0067] Wherein, the coincidence event data is the coincidence event data detected by two detectors within a preset time window, and each crystal pair (two detectors) in the PET system can output coincidence event data with consistent counts, so that the image processing module of the PET system can construct a PET system image based on the coincidence event data with consistent counts output by the detector, that is, the single photon events collected by two detectors can determine a coincidence event.

[0068] Specifically, since the final PET system reconstructs the image according to the coincidence event data to obtain the nuclide distribution map of the emitted positrons, after determining the efficiency correction coefficient of each detector, the efficiency correction coefficient corresponding to the original coincidence event also needs to be determined. When determining the efficiency correction coefficient corresponding to the original coincidence event, the first detector and the second detector corresponding to the original coincidence event need to be determined in each detector first, and then the efficiency correction coefficient corresponding to the original coincidence event is determined through the efficiency correction coefficients of the two detectors corresponding to the original coincidence event.

[0069] 206. Multiply the efficiency correction coefficient corresponding to the first detector by the efficiency correction coefficient corresponding to the second detector to obtain the efficiency correction coefficient corresponding to the original coincidence event data.

[0070] Specifically, after determining the first detector and the second detector corresponding to the original coincidence event, the efficiency correction coefficient of the first detector is multiplied by the efficiency correction coefficient of the second detector, and the product is taken as the efficiency correction coefficient corresponding to the original coincidence event. For example, if the original coincidence event 1 corresponds to the detector 1 and the detector 3, the efficiency correction coefficient corresponding to the detector 1 is multiplied by the efficiency correction coefficient corresponding to the detector 3, and finally the product is determined as the efficiency correction coefficient corresponding to the original coincidence event 1. If the original coincidence event 2 corresponds to the detector 4 and the detector 5, the efficiency correction coefficient corresponding to the detector 4 is multiplied by the efficiency correction coefficient corresponding to the detector 5, and finally the product is determined as the efficiency correction coefficient corresponding to the original coincidence event 2.

[0071] Further, in order to correct the original coincidence event data detected by the PET system, after step 207, the method further comprises: multiplying the efficiency correction coefficient corresponding to the original coincidence event data by the original coincidence event data to obtain corrected coincidence event data.

[0072] Specifically, after determining the efficiency correction coefficient of the original coincidence event data corresponding to the PET system, when the PET system is working, the computer device obtains the original coincidence event data according to the scanning data of each position obtained by each detector in the PET system scanning the uniform radioactive source phantom moving to each position, multiplies the efficiency correction coefficient corresponding to the original coincidence event data by the original coincidence event data to obtain the corrected data corresponding to the original coincidence event data, and finally uses the corrected data to perform image reconstruction to obtain the nuclide distribution map of the positron emitting.

[0073] According to the PET system correction method provided by the application, compared with the current method of collecting coincidence data by using a phantom with a length capable of covering the axial field of view of the PET system, and then calculating the PET system efficiency correction coefficient by means of the collected coincidence data, the single photon counting values collected by each detector in the PET system are obtained, wherein the single photon counting value is the number of single photons generated by the radioactive source phantom and collected by each detector in the process of moving the radioactive source phantom along the axial direction of the PET system, and the length of the radioactive source phantom is less than the length of the axial field of view of the PET system; the efficiency correction coefficient of each detector is calculated based on the single photon counting values collected by each detector; and the efficiency correction coefficient of the corresponding original coincidence event data of the PET system is determined according to the efficiency correction coefficient of each detector, wherein the efficiency correction coefficient of the original coincidence event data is used for correcting the detection efficiency of the PET system. Thus, by using a shorter uniform radioactive source phantom, the radioactive source axial center line is required to be aligned with the PET system axial center line, at the same time, the radioactive source phantom is controlled to move along the PET system axial center line to collect the single photon counting values of each detector, then the efficiency correction coefficient of each detector is calculated according to each single photon counting value, and finally the original coincidence event data collected by the PET system is corrected, so that the detector efficiency correction coefficient can be quickly and accurately determined, and the efficiency correction cost of the PET system detector can be reduced, thereby avoiding the problems of difficult phantom manufacturing, high manufacturing cost, large phantom operation difficulty and long operation time caused by using a longer phantom to determine the detector efficiency correction coefficient in the prior art.

[0074] Further, as a specific implementation of Figure 1 , the embodiment of the application provides a PET system correction device, as shown in Figure 3 , the device comprises an acquisition unit 31, a calculation unit 32 and a determination unit 33.

[0075] The acquisition unit 31 can be used to acquire single photon counting values collected by each detector in the PET system, wherein the single photon counting value is the number of single photons generated by the radioactive source phantom and collected by each detector in the process of moving the radioactive source phantom along the axial direction of the PET system, and the length of the radioactive source phantom is less than the length of the axial field of view of the PET system.

[0076] The calculation unit 32 can be used to calculate the efficiency correction coefficient of each detector based on the single photon counting values collected by each detector.

[0077] The determination unit 33 can be used to determine the efficiency correction coefficient of the corresponding original coincidence event data of the PET system according to the efficiency correction coefficient of each detector, wherein the efficiency correction coefficient of the original coincidence event data is used for correcting the detection efficiency of the PET system.

[0078] In a specific application scenario, in order to obtain the single photon count value collected by each detector in the PET system, the obtaining unit 31 comprises a first determining module 311 and an accumulating module 312.

[0079] The first determining module 311 can be configured to determine the effective radiation site of the radiation source phantom according to the geometric parameter information of the radiation source phantom.

[0080] The accumulating module 312 can be configured to sequentially accumulate the single photon counts collected by each detector based on the head real-time position information, the tail real-time position information in the axial direction of the PET system, and the position information of each detector in the effective radiation site, to obtain the single photon count value of each detector.

[0081] In a specific application scenario, in order to control the movement of the radiation source phantom along the axial direction of the PET system, the device further comprises a control unit 34.

[0082] The control unit 34 can be configured to control the radiation source phantom to move along the axial center line of the PET system in a uniform linear motion manner, wherein the radiation source phantom is a uniform axial center symmetric phantom, and the axial center line of the radiation source phantom coincides with the axial center line of the PET system.

[0083] In a specific application scenario, in order to determine the moving speed and moving period of the radiation source phantom, the determining unit 33 can further be configured to determine the half-life period of the radiation source phantom, and determine the moving speed and the number of movements of the radiation source phantom along the axial center line of the PET system based on the half-life period.

[0084] In a specific application scenario, in order to calculate the efficiency correction coefficient of each detector, the calculating unit 32 comprises an accumulating module 321 and a dividing module 322.

[0085] The accumulating module 321 can be configured to accumulate the single photon count values collected by each detector to obtain a single photon count sum of the PET system.

[0086] The dividing module 322 can be configured to determine a single photon count mean value based on the number of detectors and the single photon count sum, and determine the ratio of the single photon count mean value to each single photon count value as the efficiency correction coefficient of each detector.

[0087] In a specific application scenario, in order to determine the efficiency correction coefficient of the original coincidence event data corresponding to the PET system, the determining unit 33 comprises a second determining module 331 and a multiplying module 332.

[0088] The second determining module 331 can be configured to determine the first detector and the second detector corresponding to the original coincidence event data.

[0089] The multiplication module 332 can be configured to multiply the efficiency correction coefficient corresponding to the first detector and the efficiency correction coefficient corresponding to the second detector to obtain the efficiency correction coefficient corresponding to the raw coincidence event data.

[0090] In a specific application scenario, in order to correct the raw coincidence event data obtained by the PET system, the device further comprises a correction unit 35.

[0091] The correction unit 35 can be configured to multiply the efficiency correction coefficient corresponding to the raw coincidence event data and the raw coincidence event data to obtain the corrected coincidence event data.

[0092] It should be noted that other corresponding descriptions of the functions of the PET system efficiency correction device provided by the embodiments of the present application can be referred to the corresponding descriptions of the method shown in Figure 1 , which will not be repeated here.

[0093] Based on the method shown in Figure 1 , correspondingly, the embodiments of the present application also provide a computer readable storage medium, which stores a computer program, and the program is executed by a processor to realize the following steps: obtaining single photon counting values collected by each detector in a PET system, wherein the single photon counting value is the number of single photons generated by a radioactive source phantom collected by each detector in the process of moving the radioactive source phantom along the axial direction of the PET system, and the length of the radioactive source phantom is less than the axial field of view length of the PET system; calculating efficiency correction coefficients of each detector based on the single photon counting values collected by each detector; determining the efficiency correction coefficient of the raw coincidence event data corresponding to the PET system according to the efficiency correction coefficients of each detector, wherein the efficiency correction coefficient of the raw coincidence event data is used to correct the detection efficiency of the PET system.

[0094] Based on the method shown in Figure 1 and the device shown in Figure 4 , the embodiments of the present application further provide an entity structure diagram of a computer device, as shown in Figure 5As shown, the computer device comprises a processor 41, a memory 42, and a computer program stored on the memory 42 and executable on the processor, wherein the memory 42 and the processor 41 are both arranged on a bus 43, and the processor 41 implements the following steps when executing the program: acquiring single photon count values collected by each detector in a PET system, wherein the single photon count value is the number of single photons generated by a radioactive source phantom collected by each detector in the process of moving the radioactive source phantom along the axial direction of the PET system through each detector, and the length of the radioactive source phantom is less than the axial field of view length of the PET system; calculating the efficiency correction coefficient of each detector based on the single photon count values collected by each detector; and determining the efficiency correction coefficient of the corresponding raw coincidence event data of the PET system according to the efficiency correction coefficient of each detector, wherein the efficiency correction coefficient of the raw coincidence event data is used to correct the detection efficiency of the PET system.

[0095] Through the technical scheme of the present application, the single photon count values collected by each detector in a PET system are acquired, wherein the single photon count value is the number of single photons generated by a radioactive source phantom collected by each detector in the process of moving the radioactive source phantom along the axial direction of the PET system through each detector, and the length of the radioactive source phantom is less than the axial field of view length of the PET system; the efficiency correction coefficient of each detector is calculated based on the single photon count values collected by each detector; and the efficiency correction coefficient of the corresponding raw coincidence event data of the PET system is determined according to the efficiency correction coefficient of each detector, wherein the efficiency correction coefficient of the raw coincidence event data is used to correct the detection efficiency of the PET system. Thus, by using a shorter uniform radioactive source phantom, the radioactive source axial center line and the PET system axial center line are required to be aligned, at the same time, the radioactive source phantom is controlled to move along the PET system axial center line to collect the single photon count values of each detector, then the efficiency correction coefficient of each detector is calculated according to each single photon count value, and finally the raw coincidence event data collected by the PET system is corrected, which can quickly and accurately determine the detector efficiency correction coefficient, at the same time, can reduce the efficiency correction cost of the PET system detector, and avoid the problems of difficult production, high production cost, large operation difficulty and long operation time of the long phantom for determining the detector efficiency correction coefficient in the prior art.

[0096] It should be apparent to those skilled in the art that the modules or steps of the application described above can be implemented with a general purpose computing device, which can be centralized on a single computing device or distributed over a network of multiple computing devices, and optionally implemented with program code executable by a computing device, which can be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described can be performed in a different order than shown, or made into individual integrated circuit modules, or multiple modules or steps made into a single integrated circuit module. Thus, the application is not limited to any particular combination of hardware and software.

[0097] The preferred embodiments of the application described above are intended to be merely exemplary and those skilled in the art will recognize that changes can be made to the above-described embodiments without departing from the spirit and scope of the application. What is desired to be protected by letters patent is set forth in the appended claims.

Claims

1. A method of calibration of a PET system, characterized in that, The method comprises: acquiring single photon count values collected by each detector in a PET system, wherein the single photon count value is the number of single photons collected by each detector generated by a radioactive source phantom during the movement of the radioactive source phantom along the axial direction of the PET system, and the length of the radioactive source phantom is less than the axial field of view length of the PET system; calculating the efficiency correction coefficient of each detector based on the single photon count values collected by each detector; determining the efficiency correction coefficient of the corresponding raw coincidence event data of the PET system according to the efficiency correction coefficient of each detector, wherein the efficiency correction coefficient of the raw coincidence event data is used to correct the detection efficiency of the PET system; wherein the calculation of the efficiency correction coefficient of each detector based on the single photon count values collected by each detector comprises: accumulating the single photon count values collected by each detector to obtain the single photon count sum collected by the PET system, determining the single photon count mean based on the number of detectors and the single photon count sum, and determining the ratio of the single photon count mean to each single photon count value as the efficiency correction coefficient of each detector; determining the efficiency correction coefficient of the corresponding raw coincidence event data of the PET system according to the efficiency correction coefficient of each detector, wherein the efficiency correction coefficient of the raw coincidence event data is used to correct the detection efficiency of the PET system; determining the first detector and the second detector corresponding to the raw coincidence event data; multiplying the efficiency correction coefficient corresponding to the first detector and the efficiency correction coefficient corresponding to the second detector to obtain the efficiency correction coefficient corresponding to the raw coincidence event data.

2. The method of claim 1, wherein, The acquisition of the single photon count values collected by each detector in the PET system comprises: determining the effective radiation site of the radioactive source phantom based on the geometric parameter information of the radioactive source phantom; based on the head real-time position information, the tail real-time position information along the axial direction of the PET system, and the position information of each detector, the single photon counts collected by each detector are sequentially accumulated to obtain the single photon count values of each detector.

3. The method of claim 1, wherein, The method further comprises: controlling the radioactive source phantom to move through each detector along the axial center line of the PET system in a uniform linear motion, wherein the radioactive source phantom is a uniform axial center symmetric phantom, and the axial center line of the radioactive source phantom coincides with the axial center line of the PET system.

4. The method of claim 3, wherein, The method further comprises: determining the half-life of the radioactive source phantom; based on the half-life, determining the moving speed and the moving times of the radioactive source phantom along the axial center line of the PET system.

5. The method of claim 1, wherein, After multiplying the efficiency correction coefficient corresponding to the first detector and the efficiency correction coefficient corresponding to the second detector to obtain the efficiency correction coefficient corresponding to the raw coincidence event data, the method further comprises: multiplying the efficiency correction coefficient corresponding to the raw coincidence event data and the raw coincidence event data to obtain the corrected coincidence event data.

6. A correction device of a PET system, characterized in that, The method comprises: An acquisition unit is configured to acquire single photon count values collected by each detector in a PET system, wherein the single photon count values are numbers of single photons generated by a radioactive source phantom in a process in which the radioactive source phantom moves along an axial direction of the PET system through each detector, and a length of the radioactive source phantom is less than a length of an axial field of view of the PET system; A calculation unit is configured to calculate efficiency correction coefficients of the detectors based on the single photon count values collected by each detector, wherein the calculation of the efficiency correction coefficients of the detectors based on the single photon count values collected by each detector includes: accumulating the single photon count values collected by each detector to obtain a single photon count sum collected by the PET system; determining a single photon count mean based on a number of detectors and the single photon count sum, and determining a ratio of the single photon count mean to each single photon count value as the efficiency correction coefficient of each detector; A determination unit is configured to determine an efficiency correction coefficient of original coincidence event data corresponding to the PET system according to the efficiency correction coefficients of the detectors, wherein the efficiency correction coefficient of the original coincidence event data is used to correct a detection efficiency of the PET system, and the determination of the efficiency correction coefficient of the original coincidence event data corresponding to the PET system according to the efficiency correction coefficients of the detectors includes: determining a first detector and a second detector corresponding to the original coincidence event data; and multiplying the efficiency correction coefficient corresponding to the first detector and the efficiency correction coefficient corresponding to the second detector to obtain the efficiency correction coefficient corresponding to the original coincidence event data.

7. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by a processor to implement the steps of the method in any one of claims 1 to 5.

8. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The computer program is executed by a processor to implement the steps of the method in any one of claims 1 to 5.

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